OpenStudio Visualizes Energy Use in Buildings

March 8, 2011

Look around you. Odds are, you are indoors reading this story using a computer or
mobile device, perhaps sipping on a favorite cup of coffee. If you are indoors at
this moment, you're draining energy from one of the largest consumers of energy in
the U.S. — a building.

Together, residential and commercial buildings account for a staggering 40 percent
of energy use in the United States. However, the U.S. Department of Energy's (DOE)
National Renewable Energy Laboratory (NREL) is developing a suite of tools to tame
this energy beast — and it is free to anyone who wants to use it.

Whether retrofitting existing buildings or designing new buildings, energy modeling
is a core component to changing a building from an energy guzzler to an energy sipper.
"It's much cheaper to run an energy model than it is to build the wrong building or
do the wrong retrofit," said NREL Senior Engineer Nicholas Long.

DOE's EnergyPlus is a powerful simulation engine that provides comprehensive building energy modeling.
NREL is working to add tools to EnergyPlus, via its OpenStudio Application Suite,
to improve overall functionality and make EnergyPlus easier to use.

New Tools Help Carve out Energy Savings

OpenStudio software developers Larry Brackney, David Goldwasser and Nicholas Long
appear in one of the Open Studio computer visualizations that helped to design the
RSF building at NREL.
Credit: Dennis Schroeder and David Goldwasser

"The easiest way to describe OpenStudio is a wrapper on top of EnergyPlus," Long said.
"OpenStudio handles the building geometry, building envelope, plug loads, people and
daylighting, along with many other inputs. It adds all of that data into one big
massive engine and spits out results. Industry professionals will find that OpenStudio
will help them quickly and easily analyze the energy use in their buildings."

The first version of OpenStudio was released in 2008 and is a plug-in that leverages
Google SketchUp, a user-friendly 3-D drawing program. "OpenStudio was originally developed
so people could view and edit geometry for EnergyPlus models," NREL OpenStudio Developer
David Goldwasser said. "We've now expanded it to be able to view and edit a lot of
the other attributes of EnergyPlus building models, for example putting in loads like
lights, equipment and simple HVAC systems."

"OpenStudio goes a long way towards easing workflows for industry professionals,"
said Larry Brackney, NREL manager for analysis tools in commercial buildings. "We've
enhanced it and there are a slew of new features — some of which NREL has developed
and some of which we are just leveraging from Google and their massive investment
in SketchUp."

The new suite of OpenStudio tools includes the SketchUp plug-in plus:

ModelEditor which provides users with a simpler way to edit the building model. It includes a
way to access components that don't have a physical representation in a building,
like a mechanical system.

ResultsViewer, a way to review EnergyPlus simulation data in a graphical format. It allows users
to look at the data, draw conclusions and compare results.

RunManager, an application to run simultaneous simulations. This powerful tool can be used to
run simulations on a desktop, computer cluster or even a super computer. Designers
can compare results between differing models to see where the best energy savings
can be achieved.

The OpenStudio plug-in also heavily leverages a feature in SketchUp called Match Photo
which uses photographs of a building to create a 3D model — almost effortlessly.
Once the 3D model is finished, users can use the plug-in to trace over windows and
doors for EnergyPlus' use in running an energy model. It's a tool that developers
believe fills a need, especially for crews planning a building retrofit. "I see Match
Photo as a killer app because this is an area that's not been well served in the market,"
Brackney said.

"We really appreciate Google's integration goals. We think that with a lot of the
things they are connecting — like Google Earth and Building Maker and SketchUp — there
is collaboration between all of these technologies. It is creating this rich set of
building geometry models that we can use for energy modeling. There's a great synergy
there between what they are doing and what we are trying to do."

Open Source Makes User Customization Easy

OpenStudio leverages Google Sketch-up to create 3-D building geometry. Designers used
the program to create energy models for NREL's Research Support Facility.
Credit: Roger Hedrick, Architectural Energy Corporation and David Goldwasser, NREL

Although collaboration with Google is important to the NREL development team, more
important is collaboration with OpenStudio users.

"OpenStudio uses open source code so if someone wants a feature that we don't have
the time or the funds to write, there are two options," Goldwasser said. "First, they
can write that code and submit it to us. We look at it and decide if it gets accepted
and works with what we want. Another option is for them is to use an API [application
programming interface] and 'plug-in' to our software and write applications without
changing our code."

OpenStudio is made available to anyone under the GNU Lesser General Public License,
which allows third-parties to easily integrate the functionality into their applications
without requiring them to contribute their code back. "We're not selling this product,
it's free. And, what's nice about it being open source is that someone can integrate
it into their workflow," said Brackney.

For users, "our goal at NREL is to help people design buildings that are more efficient
so that we use less energy," added Brackney.

To show how easy it is to develop an API to "plug-in" to OpenStudio, NREL developed
a simple API for Heating, Ventilation, and Air Conditioning (HVAC) modeling. "SystemOutliner
is a graphical user interface for constructing HVAC systems, which has been one of
EnergyPlus' Achilles' heels," Brackney said. "It's an awesome example of how quickly
users can build a very deep, meaningful user interface to OpenStudio that meets a
real need."

The OpenStudio team L-R: Nicholas Long, Evan Weaver, Robert Guglielmetti, Alex Swindler,
Kyle Benne, David Goldwasser, Marjorie Schott, Dan Macumber, Larry Brackney, Elaine
Hale, Luigi Gentile Polese and Brent Griffith appear in front of an Open Studio computer
visualization of the RSF building at NREL. Not pictured are team members Katherine
Fleming, Jonathan Crider, Larry Ramey, and Jason Turner.
Credit: Dennis Schroeder and David Goldwasser

"The key is all about accessibility, making the notion of doing energy modeling more
and more accessible and eliminating the excuse for not doing energy modeling."

Another potential barrier to using any new software is training; but NREL has seen
to the user's needs here as well. "We have extensive online video tutorials on how
to use the new OpenStudio tools to help get users up and running sooner," Long said.

In fact, the OpenStudio Web site and YouTube Channel have nearly two hours of videos
that walk users through differing workflow applications for the program. The site
also has full documentation for the API and source code to browse, and it is continually
being updated by NREL staff.

"What's great is that if I get a lot of questions on a certain subject, I can add
in documentation on the fly and I don't have to wait for the next release," Goldwasser
said.

There is also a user's forum moderated by NREL for people to post questions and ideas
for OpenStudio.

"The user support we provide is incredible," Goldwasser added. "We provide a quick
response, and if it's a valid question, it might result in a new training video."

"I'm really pleased with the way NREL is approaching this software development," Brackney
said." We've got a full-blown software development team using rigorous software development
process to produce a quality product that people can use to see if there are any other
energy savings they can squeeze out of their buildings."